What is this - a sharpening stone?

[Seemore]

My neighbor came out with this while he and I were talking about my interest. Is this for sharpening, do you think? It has sparkles and glazed spots, and raises a thin neutral grey slurry. Sorry for the large files - I like to upload smaller files, but they sometimes get turned 90 degrees regardless of what I do. Thanks.
Dimensions:
L 9.75” (250mm ish)
W 1.375” (35mm)
H 0.375” (9.5mm)

 

[stringer]

I have a few. Interesting historical artifact. It would be worth something if you had a pristine new one with a label. One of the first commercially mined sharpening stones and the start of the Pike corporation. Pike Lisbon Chocolate Hone. Made of mica schist. Useful for sharpening softer farm implements and rough tools.

 

[stringer]

That one was probably originally marketed as a scythe sharpener.

 

[Seemore]

That one was probably originally marketed as a scythe sharpener.

Thank you.

 

[stringer]

Here's my sparkliest one.

 

[Legion74]

I'm not sure that is a Chocolate hone. It looks more like silicon carbide, the type sold to be used for garden tools, lawn mower blades, etc.

 

[stringer]

I'm not sure that is a Chocolate hone. It looks more like silicon carbide, the type sold to be used for garden tools, lawn mower blades, etc.

These things are way softer than any SiC I have encountered. And SiC stones don't generally contain mica schist. It might not be a chocolate hone, but I am pretty sure they are natural. I have three or four now. One that's nearly identical to OP. Same dimensions, color, etc. I have never seen a labelled one in person. So take that what you will. Another option is the closely related Indian Pond. Also a mica schist. Here's a labeled one.

https://www.worthpoint.com/worthopedia/vintage-pikes-indian-pond-scythe-1823184369

 

[Seemore]

Here's my sparkliest one.

View attachment 249440

Afterthought: Before I posed my question, I sharpened a small western mono carbon knife on it. I wanted to see if there was any release of particles, so that I could mention it in my original post. That knife is cutting ripe cherry tomatoes better than anything else in my arsenal.

 

[Matus]

Looks a bit like the stone that was (and still is!) mined in Slovakia:

Kameň Rozsutec

 

[deltaplex]

I have a handful of these as well, I find them interesting as a natural stone, but not too terribly useful for kitchen knives (yet, I haven't dedicated a ton of time to them).

 

[bsfsu]

These things are way softer than any SiC I have encountered. And SiC stones don't generally contain mica schist. It might not be a chocolate hone, but I am pretty sure they are natural. I have three or four now. One that's nearly identical to OP. Same dimensions, color, etc. I have never seen a labelled one in person. So take that what you will. Another option is the closely related Indian Pond. Also a mica schist. Here's a labeled one.

https://www.worthpoint.com/worthopedia/vintage-pikes-indian-pond-scythe-1823184369

I think you're right here, I picked one up a few months ago. The only time I've used it was for sharpening a vic tournée knife but it was quite low grit.